Popa: I don’t get you
Your story of Rav Yaakov makes the point that chinuch is about deciding on the appropriate behaviour for different ages. This is an obvious principle.
I wouldn’t discipline, say, a five year old for loud, impolite comments about the lady crossing the street, nor a six year old for knocking down a light fixture while playing with a broomstick, etc, etc, etc (I use ‘survival’ techniques for those, not ‘chinuch’ techniques)
In my experience, your specific application of this principle is incorrect. ‘Talking dirty’ is usual for a 3-4 year old, but not a 7 year old.